An employee scheduling software made by a local start-up of the same name, ZoomShift puts requests for time off all in one place, allows workers to trade shifts, and gives Payne the power to track hours and wages while he creates the schedule. When he's finished, he can distribute it via email and text messages with just one click.

"This is the fourth or fifth scheduling software we looked at, and by far it's the easiest," Payne said.

Making things easy — building simple products that solve people's problems — is the starting point for ZoomShift Inc.'s founders, neither of whom had much software code-writing experience before starting the company.

Ben Bartling, then a finance major at Marquette University, saw a need for scheduling software for smaller businesses after working in a restaurant, and started ZoomShift in 2011. He met co-founder Jon Hainstock, who earned his advertising degree from Ball State University, at a technology accelerator.

Bartling had created an initial product, but the co-founders began teaching themselves the intricacies of software coding, a three-year process that led to the relaunch of ZoomShift in spring 2013. Drawing on thousands of Google searches and the online CodeIgnitor series, they learned almost everything they needed to know to develop the new ZoomShift, Hainstock said.

"Hiring coders is definitely a way you can do it. But we like getting our hands dirty and doing that kind of stuff," he said.

In its first year of existence, ZoomShift raised about $60,000 from 94labs, a Milwaukee start-up accelerator. But by the end of 2011, 94labs was having financial problems and the accelerator folded.

Bartling and Hainstock started Tailwind Creative, a web design agency they thought could provide support and allow them to develop ZoomShift. They would be self-taught and self-funded.

Tailwind got its biggest client, inbound.org, when Bartling and Hainstock built a jobs board for the marketing website — even though the site's organizers said they weren't interested.

Dharmesh Shah and Rand Fishkin, inbound's creators, were so impressed they continued to hire Tailwind for other projects, Shah said.

Bootstrapping works for ZoomShift's founders because they've got the drive to balance their consulting work with the job of building a start-up from scratch, said Shah, who is also chief technology officer at HubSpot, a Cambridge, Mass., company whose marketing software helps businesses attract customers on the web. Shah also is co-author of "Inbound Marketing: Get Found Using Google, Social Media and Blogs," and writes a blog called OnStartups.com.

Bartling and Hainstock are craftsmen when it comes to code, Shah said.

"They love writing software that is elegant, simple and most important of all, that is easy to maintain. This is a relatively rare quality among developers," Shah said.

A year after rereleasing ZoomShift, the company has several hundred customers at restaurants, retail stores and other businesses that hire hourly workers, Hainstock said. That translates into thousands of users each day.

The product is marketed online and sold around the world, Hainstock said.

"They're very focused on design and customer acquisition, and they're a great model other start-ups in Milwaukee should follow," said Matt Cordio, co-founder of Startup Milwaukee, an entrepreneurs group.

Millions of organizations are potential ZoomShift customers, Shah said. But because the market is so large and diffuse, ZoomShift — like most software as a service companies — will face challenges acquiring those customers efficiently so that the economics make sense.